With the growing consciousness in many countries of the adverse effects of alcohol, with greater restrictions on drunken driving and underage drinking, and in some cases with legal or religious restrictions, many beverage manufacturers have recognized a market for low or near zero alcohol content wines, beers, and other fermented drinks. To achieve the full flavor of a beer or varietal wine, it is necessary to manufacture the alcoholic beverage and then remove the ethanol, while preserving as much as possible of the remainder of the flavor components. It is this last aspect that makes most technologies for removing alcohol less than satisfactory. In particular, processes that require heating of the beverage either change the nature of some of the flavor components or drive off the volatile essences that provide the flavor.
Various means have been used in the past to separate alcohol from liquids. For example, reverse osmosis has been used but is disadvantageous in that high pressures must be used and the separation process is one involving liquid phase transfer across a barrier causing water loss as well.
Dialysis has been used in U.S. Pat. No. 4,581,236. The transfer membrane in dialysis is one that generally permits passage of small molecules but not large ones. Transfer does not occur in the vapor phase and some flavor components pass through the membrane in addition to the alcohol.
U.S. Pat. No. 4,781,837 covers a process identified as osmotic distillation. This patent does not teach removal of alcohol from an aqueous solution; but, describes the use of a porous hydrophobic barrier to transfer, in vapor phase, a solvent from a liquid of lower osmotic pressure to a liquid of higher osmotic pressure. When applied to fermented liquids, water in fermented liquids passes through in addition to the alcohol, necessitating re-adding water to the concentrated fermented liquid. Furthermore, the osmotic pressure differential is attained by using a brine solution which can contaminate the fermented liquid should a hole develop in the barrier. It would be beneficial to provide a simple, straight-forward procedure for separating alcohol from liquids.